The invention relates to a safety binding for ski boot, in particular, the invention relates to the means for controlling release of the ski bindings such as described in document CH 686 707 the contents of which are incorporated herein by reference thereto, in order, more simply, to produce an asymmetrical or symmetrical binding with automatic positioning by the boots using a sole clamp and a piston.
The sole clamp is preferably divided into two independent sole clamps, each mounted so as to pivot about an individual axis.
A binding of this type, which includes a single sole clamp and a single piston, is known from patent CH 686 707. This binding has the advantage of controlling, by means of a spring placed under the bearing surface of the boot on the binding, not only the pivoting of the sole clamp about a vertical axis in the event of a fall, but also the rocking of the sole clamp in a vertical plane. The arrangement of the spring under the bearing surface of the boot makes it possible to have a favorable relationship between the load moments exerted on the boot in the horizontal plane and in the vertical plane. A binding of the same type, but one which includes two sole clamps is known. The sole clamps constitute two levers of the first class, having divergent arms for laterally holding the boot, and two convergent arms substantially perpendicular to the longitudinal axis and each equipped with a descending arm bearing at two points which are close to one another on the end of a piston mounted axially in the body of the binding extending under the boot and pushed by a spring. The presence of two sole clamps with two close bearing points makes it possible to reduce the lateral forces on the piston and, consequently, to reduce the friction forces opposing the sliding of the piston. The friction of the sole clamps on the flange of the boot is also less than in a binding with a single sole clamp. According to an embodiment shown in that document, the sole clamps bear on two parallel pistons, but it is revealed that it is preferable to have a single piston common to the two sole clamps. The inventor has thus not seen the advantage he could draw from having two pistons.
Patents FR 1 503 847, 1 503 848, and 1 503 849, the contents of which are incorporated by reference, furthermore disclose bindings with resistance to asymmetric release in order to take account of the fact that the skier""s knee, subject to twisting forces at the time of a fall, is more vulnerable to an inward rotation of the foot than to an outward rotation of the foot. As these bindings require pairing between boots and skis, i.e. a left ski for the left foot, and a right ski for the right foot, and as swapping the skis round has an effect which is the reverse of the desired effect, which may have serious consequences, a binding has been sought which adapts automatically to the boot when the boot is fitted into the binding. The skier can thus fit his boot into either ski as he is accustomed to doing, with the advantage of having bindings with lower resistance to release in the event of stresses from inward rotation of the foot than in the event of outward rotation. Such bindings are described in documents U.S. Pat. No. 5,639,108, the content of which is incorporated by reference, U.S. Pat. No. 5,722,679, the content of which is incorporated by reference, WO 96/32168, the content of which is incorporated by reference, and EP 0 739 646, the content of which is incorporated by reference. These bindings have in common a conventional design for the toe piece, i.e. a spring arranged in front of the sole clamp, at the location of the boot flange. The sole clamp is either in a single piece, with the spring pivoting with the sole clamp (U.S. Pat. No. 5,639,108), or in two components, in the form of a lever bearing on a rod (U.S. Pat. No. 5,722,679, WO 96/32168, EP 0 739 646). The binding is made asymmetrical by means of a complex mechanism controlled magnetically or electromagnetically by the boot equipped, for this purpose, with bosses or with a permanent magnet.
A safety binding for ski boot, of which the sole has a flange comprising a binding body of which a horizontal part, intended for vertical support of the boot and extending under the boot, contains a pair of movable pistons stressed by elastic means, and another part carries a sole clamp for holding the boot via its flange, this sole clamp being mounted so as to pivot about an at least approximately vertical axis in order to release the boot, and pivoting by an angle limited in a vertical plane about a real or virtual axis located at the location of holding of the boot by the sole clamp, this sole clamp being equipped with two descending arms rigidly connected to the sole clamp, the ends of which bear respectively on each of the pistons.
The sole clamp is preferably divided into two independent sole clamps, each mounted so as to pivot about an individual axis.
The object of the present invention is to take advantage of the presence and of the arrangement of the two pistons of the means for controlling release of the bindings described in document CH 686 707 in order, more simply, to produce an asymmetrical or symmetrical binding with automatic positioning by the boots.
The binding according to the invention is defined in that the elastic means consist of two parallel springs on which each of the pistons bears, respectively, wherein the pistons are connected together by a linking means, and wherein the binding comprises means for controlling this linking means which are capable of occupying a first position, in which the pistons are secured by the linking means, and a second position in which one of the pistons is able to move on its own, at least over a certain travel common to the two pistons and over at least a portion of the total travel of the two pistons.
Like the pistons and the springs, the control means may be arranged entirely under the boot bearing plate. The necessary mechanism is relatively simple and compact.
The sole clamp is preferably divided into two independent sole clamps, each mounted so as to pivot about an at least approximately vertical individual axis and consisting of two levers of the first class having two divergent lever arms for laterally holding the boot, and two convergent arms at least approximately perpendicular to the longitudinal axis of the binding and bearing, respectively, on the end of each of the pistons via a descending arm at two points which are close to one another.
According to one embodiment of the invention, the linking means consists of a small bar articulated to each of the pistons.
Clearance is provided at at least one of the articulations or in the guiding of the pistons in order to allow the small bar to pivot.
The binding may thus be used either as an asymmetrical binding or as a conventional symmetrical binding.
According to one embodiment, the means for positioning the small bar comprise means for controlling the small bar comprising means for holding the small bar in its median position, these holding means being able to occupy two positions, i.e. a position in which the small bar is held or a position in which the small bar is released.
According to one embodiment, the means for holding the small bar comprise a pair of independent holding components holding the small bar on each side via its sides.
According to embodiments, the means for controlling the small bar comprise components made from ferromagnetic material or permanent magnets so as to be able to be actuated by a boot equipped with a permanent magnet.
The holding components consist of rockers or of studs that are movable in translation perpendicularly to the plane of the binding. These rockers and these studs could themselves be made from ferromagnetic material so as to be able to be attracted by a magnet equipping the boot.
According to a further embodiment, the components for holding the small bar consist of rockers which can be rocked mechanically by studs or the like fixed on one side of the boots.
The binding also preferably comprises a second, fixed means for laterally holding the small bar, arranged such that the small bar is released only after a certain simultaneous travel of the two pistons. This second means advantageously consists of a notch in which the curved end of the small bar is engaged.